A New Practice of Streamline Simulation for Compositional and Miscible Floods

Abstract

Performance evaluation of miscible and near-miscible gas injection processes is available through conventional finite difference (FD) compositional simulation, which is widely used for solving large-scale multiphase displacement problems that always require large computation time. A step can be taken to reduce the time needed by considering low-resolution compositional simulation. The model can be adversely affected by numerical dispersion and may fail to represent geological heterogeneities adequately. The number of fluid components can possibly be reduced at the price of less accurate representation of phase behavior. Streamline methods have been developed in which fluid is transported along the streamlines instead of the finite difference grid. In streamline-based simulation, a 3D flow problem is decoupled into a set of 1D problems solved along streamlines, reducing simulation time and suppressing any numerical dispersion.Larger time steps and higher spatial resolution can be achieved in these simulationsparticularly when sensitivities runs are needed to reduce study uncertainties. Streamline-based reservoir simulation, being orders of magnitude faster than the conventional finite difference methods, may mitigate many of the challenges noted above. For gas injection, the streamlines approach could not provide a high resolution or adequate representation for the multiphase displacement. In this paper, the streamline simulations for both compositional and miscible gas injection were tested, in addition, the conventional gas injection scheme and detailed comparison between the FD simulation and the streamline approachareillustrated. Also, guidelines of how streamline can be potentially used to visualize the effect of gas displacement are presented in this paper.